Power roof ventilator



June 28, 1955 F. E. DRECHSEL POWER ROOF VENTILATOR Filed Au 4, 1951 2Sheets-Sheet 1 6 par-861608! INVEN TOR.

United States Patent" POWER ROOF VENTILATOR Fred E. Drechsel, Chicago,Ill., assignor to 11g Electric Ventilating Co., Chicago, Ill., acorporation of Delaware Application August 4, 1951, Serial No. 240,356

9 Claims. (Cl. 98-43) This invention relates generally to ventilatorsand, more particularly, to a ventilating apparatus employing acentrifugal fan for drawing air out of a room or building.

A centrifugal or blower-type fan is particularly adapted for use in aventilator which is connected to a duct system since it is capable ofbuilding up sufficient pressure to overcome the friction to the air flowwithin the ducts without overloading its driving motor. Sinceventilators of this type are generally positioned externally of abuilding, such as on a roof, it becomes necessary to provide theventilator with a housing which will protect the motor, fan, and otherinternal mechanisms from rain, snow, etc. The housing should also bedesigned so that it can be easily dismantled for servicing or cleaningof the operating mechanisms. The motor and fan should be mounted so asto minimize vibration and noise, and means should be provided forcontrolling the amount of air which may be drawn through the unit. Inaddition, it is desirable to provide a means for cooling the motor whichis separate from the main air stream of the blower so that the motorwill not be subjected to the heat, dust, grease, etc. of the main airstream. None of the previously existing centrifugal-type ventilatorscombines these desirable features.

The main objects of this invention are to provide a motor-drivenventilator unit which may be mounted on a roof, which is easilyaccessible for servicing and cleaning, and which is economical tomanufacture; to provide a motor-driven ventilator in which the motor andmotor compartment are cooled by a positive draft of cool, clean, outsideair and which is' not subjected to the main air stream of the blower; toprovide improved means for controlling the amount of air which may bedrawn through the ventilator; to provide a motor-driven ventilator whichis capable of developing sufiicient static pressure to overcome theresistance to air flow encountered in ducts or duct systems; to provideimproved means for cooling the bearing surface of the motor; and toprovide a motor-driven ventilator of this kind which is capable ofoperating quietly and smoothly over long periods of time and under allweather conditions.

An illustrative embodiment of this invention is shown in theaccompanying drawings, wherein:

Fig. 1 is a perspective view of a power roof ventilator which isconstructed in accordance with the present invention.

Fig. 2 is an exploded, perspective view of the power roof ventilatorillustrated in Fig. 1.

Fig. 3 is a partial, sectional view of the motor and baffie assemblytaken along line 3-3 of Fig. 6.

Fig. 4 is a vertical, sectional view of the power roof ventilator duringoperation with the direction of movement of the air streams indicated byarrows.

Fig. 5 is a partial, exploded view of the power roof ventilator withcertain of its parts disassembled so as to leave the motor, fan, and aircontrol means in an accessible condition.

Fig. 6 is a partial, horizontal, sectional view of the power roofventilator showing the back plate of the centrifugal fan and the mannerin which the fan is keyed to the shaft of the motor.

A power roof ventilator embodying certain of the novel features of thepresent invention is illustrated in the drawings. The illustratedventilator includes a composite housing 8, a motor 9, a centrifugal fanor blower It), a shutter assembly 11, and an air control assembly 12.The composite housing 8 comprises a base assembly 13, a frame or chassisassembly 14 which is mounted on and extends upwardly from the baseassembly 13, removable bathe assemblies 15 which are adapted to be connected to the chassis assembly 14, and a roof assembly 16 which isconnected to and covers 7 the chassis assembly 14.

The base assembly 13 of the housing 8, which is particularly illustratedin Figs. 1 and 2, is fabricated out of galvanized iron, aluminum, or thelike and includes a horizontally extending, bottom flange 17 foranchoring the base assembly to a horizontal structure such as a roof.The base assembly 13 has the form of an openbottomed box and includes aremovable front panel 18 which is adapted to be connected to flanges 19on the forward end of the base assembly 13 by suitable means such asscrews. The open bottom of the base assembly 13 provides an air inlet13.1 for the housing 8.

A downwardly and outwardly inclined louver 20 is positioned at the upperand forward edge of the base assembly 13 so as to extend over theremovable panel 13, thereby preventing rain, snow, etc. from enteringthe housing through the points formed between the removable panel 18 andthe flanges 19. The base assembly 13 includes a horizontal upper plate21 which is integrally joined in a weather-tight manner with an upwardlyextending, curved hub member 22 having an open mouth which is adapted todirect air into the region of the centrifugal fan 10. Bosses 26 extendupwardly from the upper plate 21 of the base assembly 13 adjacent itscorners for positioning the chassis assembly 14 above the base assembly13. Horizontally-positioned, channel-shaped tracks 23 are attached alongthe side and rear walls 24 and 25 in the interior of the base assembly13 for guiding and supporting the shutter assembly 11 and the aircontrol assembly 12.

The chassis assembly 14, which is illustrated in Fig. 2, is fabricatedout of welded steel or the like and is adapted to seat on the upperplate 21 on the base assembly 13.

The chassis assembly 14 includes leg members 27, upper frame members 28which extend across the top of and between the leg members 27,horizontal supporting members 29 which extend between the leg members 27adjacent the lower end of the chassis assembly 14, and outwardlyextending tab members 30 which are located at the upper corners of thechassis assembly 14. The chassis assembly 14 is proportioned so as toseat on the upper plate 21 of the base assembly 13 with the leg members27 of the chassis assembly 14 superimposed over the corners of the baseassembly 13.

Each of the leg members 27 includes a horizontal flange 31 adjacent itslower end which is apertured for positioning the leg member 27 over oneof the upwardly extending bosses 26 of the base assembly 13. The chassisassembly 14 is adapted to be rigidly attached to the base asembly 13 bymeans such as screw and washer assemblies. Each of the leg members 27also includes an outwardly extending flange 32 adjacent each of itsouter edges and a ver' tically extending slot 33 for purposes which willbe apparent in the following discussion. Each of the upper frame members28 includes an outwardly and vertically extending U-shaped section 34which is adapted to interfir with a portion of the bafile assemblies 15.

Four identical baffle assemblies are'constructed as shown in Fig. 2 andare adapted to be attached to the sides of the chassis assembly 14. Eachof the baffle assemblies 14 includes a downwardly and outwardly slopingforward wall 35, triangular-shaped side walls 36 which are integrallyconnected along the forward edges to the sides of the forward wall 35,and a short, vertical, downwardly extending, rear wall 37 which isintegrally connected at its upper edge with the forward wall 35. Theforward and side walls and 36 of each bafiie assembly 15 in cludeinwardly extending flanges 38 for supporting an open work barrier suchas a rectangular grill or steel mesh 39 therebetween. The side walls 36of each baflle assembly 15 also have hook-shaped brackets 49 attachedthereto which are proportioned so as to fit into suitable slots 33 inthe legs 27 of the chassis assembly 14. The baflle assemblies 15 areproportioned so that when the brackets fit into the slots 33 in thechassis assembly 14, the downwardly extending back plates 37 fit intothe grooves of the U-shaped sections 34 of the upper frame members 28and the side walls 36 overlap the outwardly extending flanges 32 of thechassis assembly 14, thereby insuring a weather-tight assembly whichprevents snow, rain, etc. from entering into the interior of the housing8. When the baffle assemblies 15 are positioned on the chassis assembly14, the grills 39 are located below the forward walls 35 and permit airto escape from the housing 8 while preventing birds and animals fromentering the housing 8. The openings in the grills thus constitute airoutlets for the housing 8.

A roof assembly 16 comprising a semicircular, curved top section 41 andvertical side walls 42 is adapted to be positioned over the chassisassembly 14 and to be connected thereto by means such as screws. Theroof assembly is slightly larger than the chassis assembly 14 and isadapted to seat over the upper edges of the baffle assemblies 15 so asto provide air inlet openings 16.1 in the upper portion of the housing 8and so as to prevent rain, snow, etc. from entering the upper portion ofthe housing 8. As may be seen from Figs. 1, 2, and 5, the roof assemblyis connected adjacent thebottom of its side walls 42 to the outwardlyextending tab members 30 of the chassis assembly 14. The roof assemblyincludes horizontal cross members 43 which extend between the side walls42 adjacent the longitudinally extending edges of the top section 1 16which prevent the baffle assemblies 15 from being disassembled from thechassis assembly 14 when the roof assembly 16 is secured to the chassisassembly 14. By removing the appropriate screws on the roof assembly 16,the roof assembly 16 may be hinged on two sides for I access to themotor 9.

The motor 9 and the centrifugal fan 10 are resiliently mounted withinthe housing 8 so that all vibrations due to the operation of the motor 9and the fan 10 are absorbed and dampened by the mounting means insteadof being transmitted to the housing 8. The mounting means isparticularly shown in Figs. 2 and 3 and includes a motor supportassembly 44, an air shield 45, and resilient mounting strips 46. g

The mounting strips 46 are constructed of two metallic strips '47 whichare separated by a layer of resilient material 48, such as soft, liveneoprene. The mounting strips 46 are positioned horizontally on theupper frame members 28 of the chassis assembly 14.

The air shield comprises a flat, metallic plate having the samedimensions as the upper surface of the chassis assembly 14 and ispositioned horizontally over the chassis assembly 14 and the mountingstrips 46. The air shield 45 has a central bore or opening 45.1 thereinwhich provides the only means by which air can move from the space abovethe air shield 45 to the space within the chassis assembly 14.

The motor support assembly 44 is positioned on the upper surface of theair shield 45. The motor support assembly includes a central, verticallyextending, tubular section 49 which is adapted to be positioned abovethe opening in the air shield, triangular-shaped, vertical arm sections50 which extend outwardly from the tubular section 49 so as to overliethe diagonals of the air shield 45, and horizontal flanges 51 which areconnected at the outer extremities of the arm sections 50 for attachmentof the motor support assembly 44 to the air shield 45.

The chassis assembly 14, the mounting strips 46, the air shield 45, andthe flange sections 51 of the motor support assembly 44 are apertured sothat the members may be rigidly interconnected by means such as screws.In order to minimize the vibration between the chassis assembly 14 andthe motor support assembly 44, some screws extend upwardly from thechassis assembly 14 into the mounting strips 46 and terminate short ofthe upper end of the mounting strips 46, and other screws extenddownwardly through the motor support assembly 44, the air shield 45, andinto the mounting strips 46 and terminate short of the lower end of themounting strips 46, as illustrated in Fig. 3.

The motor 9 has a generally drum shaped casing 9.1 which fits within andis connected to the tubular section 49 of the motor support assembly 44by means such as washer and screw assemblies. Horizontal slots 52 withinthe tubular section 49 allow an adjustment of the motor 9 so as tofacilitate its assembly within the motor support assembly 44. Whenassembled, the lower end of the motor casing 9.1 terminates just abovethe surface of the air shield 45. The motor 9 includes a shaft 53containing a key 54 thereon which descends downwardly of the supportassembly 44 into the interior of the chassis assembly 14. Each end ofthe motor casing 9.1 is provided with suitable air openings or ducts 55so as to permit air to circulate through the motor 9 for coolingpurposes, there being sufficient space between the internal portions ofthe motor 9 to permit air to pass therethrough. The motor 9 may beconnected in the usual manner to a suitable source of electric power bymeans of a cable which extends through an appropriate cut-out in thehousing 8 (not shown).

The centrifugal fan or rotor 10 comprises a back plate 56 which includesan outer horizontal ring-shaped section 57 and an inner concavebowl-shaped section 58, a base member 59, vertical impeller blades whichextend between the base member 59 and the ring-shaped section 57, andshort, vertical'fins 61 which are connected to and extend above thesurface of the ring-shaped section 57. The impeller blades 60 aretransversely curved so as to be effective in throwing or tangentiallydischarging the air from within the rotor 10 outwardly of the peripheryof the rotor 10. The vertical fins 61 extend radially of the back plate56 and are operable to cool the lower bearing of the motor 9, as will behereinafter described. The bowl-shaped section 58 is integrallyconnected with a vertically extending hub member 62 which includes avertically extending hole and keyway 63 which are adapted to interfitwith the shaft 53 and the key 54 associated with the motor 9. Thecentrifugal fan 10 is adapted to be fixedly positioned and freelysuspended on the shaft 53 by a nut 64 and a set screw 65. The basemember 59 extends inwardly and downwardly, as shown in Fig. 4, andincludes a vertical flange portion 66 which extends over and outwardlyof the upper portion of the hub member of the base assembly 13.

A shutter assembly 11 which is adapted to ride on either the upper orlower tracks 23 within the base assembly 13 is particularly shown inFigs. 2 and 4. The shutter assembly 11 includes angle-shaped sidemembers 67 having horizontally extending portions 68 which ride on thetracks 23 which extend along the side Walls 24 of the base assembly 13,an angle-shaped rear member 69 having a horizontally extending portion70 which interfits into the tracks 23 which extend along the rear wall24 of the base assembly 13, an angle-shaped, forward member 71 and aseries of flat, rotatable louvers 72 which are positioned parallel toeach other between the side members 67 so as to be able to overlap eachother when they are in a horizontal position. A vertically extendingplate 73 which is connected to the louvers 72 is movably mountedadjacent one side of the shutter assembly 11. An electric motor 74 whichis attached adjacent the forward end of the shutter assembly 11 isconnected with the movable plate 73 by a chain 75, or the like, forcontrolling the position of the plate 73 and the louvers 72. The motor74 is operable to move its associated shaft 76 between two predeterminedpositions. The plate 73 is also resiliently biased by a spring 77 whichextends between the plate 73 and one of the side members 67 so as toposition the louvers 72 horizontally when the motor 74 is not actuated.The motor 74 may be connected to a source of electric power by the usualcable through a cut-out 98 in the side of the base assembly 13. Themotor 74 which controls the shutter assembly 11 is interconnected withthe motor 9 which controls the centrifugal fan 10 so that they operatesimultaneously. operating, the spring 77 biases the plate 73 in adirection such that the louvers 72 lie horizontally and overlap eachother, thus closing off the space below the shutter assembly 11 from thespace above the shutter assembly 11. When the fan 10 is operated, theshaft 76 rotates so as to wind a the chain 75 therearound, therebymoving the plate 73 in opposition to the spring 77 thus forcing thelouvers 72 to their open position.

An air control assembly 12 is operable to control the quantity of airwhich is permitted to pass through the base assembly 13 into the regionof the centrifugal fan 10 and is particularly shown in Figs. 2 and 4.The air control assembly 12 slides within the tracks 23 in the baseassembly 13 in a similar manner to the shutter assembly 11 and includesa series of parallel horizontal louvers 78 which extend between thefront and rear members 79 and 86 of the air control assembly 12. Thelouvers '78 are adapted to be positioned at various angles to thehorizontal by a motor 81 which interconnects with the louvers 78 throughthe interfitting shafts 82 and 83. The motor 81 for the air controlassembly 12 is positioned exteriorly of the base assembly 13 within aspecial housing 84 which is fabricated from metal or the like. Thehousing 34 includes the member 85 which overlaps and connects to themember 86 so as to form a weather-tight protective covering for themotor 81. A cut-out 87 in the side of the motor housing 84 providesmeans for extending a cable from the motor 81 to a suitable switch andsource of power (not shown). The motor is operable to turn the shafts 82and 83 and the louvers 78 to a series of positions, thereby regulatingthe amount of air which may be passed from the space below the aircontrol assembly 12 to the space above the air control assembly 12.

A ventilator of the type described is readily accessible for cleaningand maintenance. The panel 18 at the for ward face of the base assembly13 may be removed for access to the shutter assembly 11 and the aircontrol assembly 12. Screws may be removed from the roof assembly 16 sothat the roof assembly 16 may be hinged either forwardly or rearwardlyso as to expose the motor 9 and the motor support assembly 44. When theroof assembly 16 is in raised position, the baffle assemblies may beremoved from the chassis assembly 14 so as to expose the centrifugal fan10.

When the ventilator is positioned above a duct which leads to anenclosed space, it is operable to withdraw air from that space. Sincethe motors 9 and 74 operate simultaneously the louvers 72 are in closedposition when the centrifugal fan is not in operation, thus preventingthe air within the enclosed space from escaping through the ventilator.This is extremely important during the winter when one desires to keepthe warm air within the enclosed space. However, when the centrifugalfan is in operation, the motor, 74 moves the louvers 72 to openposition, thereby permitting air to be drawn up When the centrifugal fanIt) is not &

through the air inlet 13.1 at the base of the housing 8 into the regionof the centrifugal fan 10. During operation, one may control theposition of the air control louvers 78 by the motor 81 so as to set thelouvers in any one of several different positions, thereby permittingonly a given amount of air to move from the enclosed space into theregion of the centrifugal fan 10.

In operation, air is drawn from the enclosed space upwards through theair inlet 13.1 into the center of the centrifugal fan 19 and is throwntangentially outwardly of the blades 69 of the centrifugal fan 10. Theair passes outwardly of the ventilator through the openings in thegrills 39 of the baflie assemblies 15. The motor 9 which controls thecentrifugal fan 10 is cooled by clean, outside air which is drawn intothe upper portion of the housing 8 through the air inlet 16.1 in theupper portion of the housing. The air which is drawn into the upperportion of the housing 8 is drawn through the motor 9 into thebowl-shaped section 58 of the centrifugal fan 10. The fins 61 on theback plate 56 of the centrifugal fan 10 whirl the air which is withinthe bowl section 58, thereby cooling the bearing surface of the motor 9.The movement of the main air stream tends to suck out the air within thebowl section 58 of the centrifugal fan 10 through the space between theair shield 45 and the back plate 56. The removal of air from the bowlsection 58 reduces the pressure within that region and causes more coolair to be drawn through the motor 9. This controlled movement of themain air stream and of the cool, outside air which passes through theupper portion of the housing 8 and the motor 9 is one of the improvedfeatures of the present invention and is illustrated in Fig. 4.

The ventilator described above is economical to manufacture, simple inoperation, and easily accessible for cleaning or servicing. The motor 9and the centrifugal fan 10 are resiliently mounted so as to minimizevibration and so as to be quiet in operation. The ventilator includes ameans for cooling the motor 9 with cool, clean, outside air and alsoincludes an improved means for cooling the bearing surface of the motor9. The unit also includes means for accurately controlling the amount ofair which is withdrawn by the ventilator. The unit is made weathertightso that the motor 9, centrifugal fan It), and means for controlling airare protected from rain, snow, etc.

Variations and modifications in the details of the above structure andthe parts maybe resorted to within the spirit and coverage of thefollowing claims.

I claim:

1. A power roof ventilator comprising a housing having an upper and alower portion separated by transverse plate member, an air inlet at thebottom of said housing, a centrifugal fan disposed in said lower housingportion between said air inlet and said plate member, an air outletformed by said housing adjacent the periphery of said fan, rotatablepower means mounted within said upper housing portion in coveringrelation to a, central opening through said plate member, said rotatablemeans including at least one air passageway therethrough communicatingwith said opening in the plate member and including a part extendingthrough said opening and supportedly engaging said fan for rotationtherewith, and an air inlet disposed adjacent said transverse platemember and in the upper portion of said housing whereby air may enterthe upper portion of said housing, move upwardly along the outside ofsaid rotatable means and be drawn through said rotatable means uponoperation of the latter to thereby cool said rotatable means.

2. A power roof ventilator comprising a housing having an upper and alower portion separated by a transverse plate member, an air inlet atthe bottom of said housing, a centrifugal fan disposed in said lowerhousing portion between said air inlet and said plate member, an aircontrol assembly between said inlet and said fan comprising a first setof adjustable parallel louvers set in a horizontal plane and a secondset of adjustable louvers disposed in transverse parallel relation tosaid first set of louvers, one of said sets of louvers being operablyconnected with said fan to open when the fan is operated and close whenthe fan is not rotating, an air outlet adjacent the periphery of thefan, rotatable power means mounted within said upper housing portion incovering relation to a central opening through said plate member, saidrotatable means including at least one air passageway therethroughcommunicating with said opening in the plate member, means extendingthrough said plate opening for connecting said fan with said rotatablemeans, and an air inlet in said upper housing portion.

3. A power roof ventilator comprising a housing having an upper and alower portion separated by a transverse plate member, an air inlet atthe bottom of said housing, a centrifugal fan disposed in said lowerhousing portion between said air inlet and said plate member, an airoutlet in said housing adjacent the periphery'of said fan, a motormounted within said upper housing portion in covering relation to acentral opening through said plate member, said motor having a casingwith openings in the upper and lower ends thereof, the openings in thelower end of said casing communicating with said openingin said platemember, the internal portions of said motor being arranged to permit airto pass therethrough, said motor including a motor shaft which extendsthrough said casing and the opening in said plate member andsupportingly engages said fan for rotation therewith, and an air inletdisposed in the upper portion of said housing adjacent said transverseplate member whereby air may enter the upper portion of said housing,move upwardly along the outside of said motor casing and be drawnthrough said motor upon the operation of said fan to thereby cool themotor.

4. A power roof ventilator comprising a housing having an upper andlower portion separated by a transverse plate member, an air inlet atthe bottom of said housing, a centrifugal fan disposed in said lowerhousing portion between said air inlet and said plate member, an aircontrol assembly between said air inlet and said fan comprising a firstset of adjustable parallel louvers set in a horizontal plane and asecond set of adjustable parallel louvers disposed in transverserelation to said first set of louvers, one of said sets of louvers beingoperatively connected with said fan to open when the fan is operatingand close when the fan is not operating, an air outlet in said housingadjacent the periphery of said fan, a motor mounted within said upperhousing portion in covering relation to a central opening through saidplate member, said motor having a casing with openings in the upper andlower ends thereof, the openings in the lower end of said casingcommunicating with said opening in said plate member, the internalportions of said motor being arranged to permit air to passtherethrough, said motor including a motor shaft which we tends throughsaid casing and the opening in said plate member and supportinglyengages said fan for rotation therewith, and an air inlet in said upperhousing portion.

5. A power roof ventilator comprising a housing having an upper and alower portion separated by a transverse plate member, an air inlet atthe bottom of said housing, a centrifugal fan disposed in said lowerhousing portion between said air inlet and said plate member for drawingair upwardly through said air inlet into said housing, air control meansbetween said air inlet and said centrifugal fan for limiting the amountof air drawn into said air inlet, a plurality of air outlets in saidhousing adjacent the periphery of said fan, a motor mounted within saidupper housing portion in covering relation to a central opening throughsaid plate member, said motor having a casing with openings in the upperand lower ends thereof, the openings in the lower end of said casingcommunicating with said opening in said plate member,

the internal portions of said motor being arranged to permit air to passtherethrough, said motor including a motor shaft Which-extends throughsaid casing and the opening in said plate member and supportinglyengages said fan for rotation therewith, said fan including a back platehaving upwardly extending fins for cooling the lower end of said motor,an air inlet disposed in the upper portion of said housing adjacent saidtransverse plate member whereby air may enter the upper portion of saidhousing, move upwardly on the outside of said motor casing and beingdrawn into the motor upon operation of said fan to thereby cool theinternal portions of said motor.

6. A power roof ventilator comprising a housing .55 having an upper anda lower portion separated by a transverse plate member, an air inlet atthe bottom of said housing, a centrifugal fan disposed in said lowerhousing portion between said air inlet and said plate member for drawingair upwardly through said air inlet into said housing, air control meansbetween said air inlet and said centrifugal fan for limiting the amountof air drawn into said air inlet, a plurality of air outlets in saidhousing adjacent the periphery of said fan, a motor mounted Within saidupper housing portion in covering relation to a central opening throughsaid plate member, said motor having a casing with openings in the upperand lower ends thereof, the openings in the lower end of said casingcommunicating with said opening in said plate member, the internalportions of said motor being arranged to permit air to passtherethrough, said motor including a motor shaft which passes throughsaid casing and the opening in said plate member and supportinglyengages said fan for rotation therewith, a back plate on said fan, saidback plate including an outer ring-shaped section and an innerbowl-shaped section, vertical fins extending upwardly from saidring-shaped section for cooling the lower end of said motor, an airinlet disposed in the upper portion'of said housing adjacent saidtransverse plate member whereby air may enter the upper portion of saidhousing, move upwardly on the outside of said motor casing and be drawninto the motor upon operation of said fan to thereby cool the internalportions of said motor.

7. A power'roof ventilator comprising a housing having an upper andlower portion separated by a transverse plate member, an air inlet atthe bottom of said housing, a centrifugal fan disposed in said lowerhousing portion between said air inlet and said plate member for drawingair upwardly through said air inlet into said housing, air control meansbetween said air inlet and said fan for limiting the amount of air drawninto said air inlet by said fan, a series of removable andinter-changeable baffle assemblies which form part of said housinglocated adjacent the periphery of said fan, each of said bafileassemblies including an outlet opening which is covered by an openworkbarrier for allowing air to leave said housing but which prevents birdsand animals from entering said housing, each of said baffle assembliesincluding a wall which overlies its outlet opening for preventing rainfrom entering said housing, a motor mounted within said upper housingportion in covering relation to a central opening through said platemember, said motor having a casing with openings in the upper and lowerends thereof, the openings in the lower end of said casing communicatingwith said opening in said plate member, the internal portions of saidmotor being arranged to permit air to pass therethrough, said motorincluding a motor shaft which extends through said casing and theopening in said plate member and supportingly engages said fan forrotation therewith, and an air inlet disposed in the upper portion ofsaid housing adjacent said transverse plate member, whereby air mayenter the upper portion of said housing, move upwardly along the outsideof said motor casing and be drawn through said motor upon operation ofsaid fan to thereby cool said motor.

8. A power roof ventilator comprising a housing having an upper andlower portion separated by a transverse plate member, an air inlet atthe bottom of said housing, a centrifugal fan disposed in said lowerhousing portion between said air inlet and said plate member for drawingair upwardly through said air inlet into said housing, air control meansbetween said air inlet and said fan for limiting the amount of air drawninto said air inlet by said fan, a series of removable andinter-changeable baflie assemblies which form part of said housinglocated adjacent the periphery of said fan, each of said bafileassemblies including an outlet opening which is covered by an openworkbarrier for allowing air to leave said housing but which prevents birdsand animals from entering said housing, each of said baflie assembliesincluding a wall which overlies its outlet opening for preventing rainfrom entering said housing, a motor mounted within said upper housingportion in covering relation to a central opening through said platemember, said motor having a casing with openings in the upper and lowerends thereof, the openings in the lower end of said casing communicatingwith said opening in said plate member, the internal portions of saidmotor being arranged to permit air to pass therethrough, said motorincluding a motor shaft which extends through said casing and theopening in said plate member and supportingly engages said fan forrotation therewith, the upper housing portion being proportioned so asto enclose said motor and having a lower end section which extendsslightly over and is spaced outwardly from the edges of said platemember, the space between the lower edge of said upper housing portionand the adjacent portion of said lower housing portion providing airinlets through which air may enter the upper portion of said housing,move upwardly along the outside of said motor casing and be drawnthrough said motor upon the operation of said fan to thereby cool saidmotor.

9. A power roof ventilator comprising a housing having an upper andlower portion separated by a transverse plate member, an air inlet atthe bottom of said housing, a centrifugal fan disposed in said lowerhousing portion between said air inlet and said plate member for drawingair upwardly through said inlet into said housing, an air controlassembly between said air inlet and said fan comprising a first set ofadjustable parallel louvers set in a horizontal plane and a second setof adjustable, parallel louvers disposed in transverse relation to saidfirst set of louvers, one of said sets of louvers being operativelyconnected with said fan to open when the fan is operating and close whenthe fan is not operating, a series of removable and inter-changeablebaflie assemblies which form part of said housing located adjacent theperiphery of said fan, each of said bafile assemblies including anoutlet opening which is covered by an openwork barrier for allowing airto leave said housing but which prevents birds and animals from enteringsaid housing, each of said baffle assemblies including a wall whichoverlies the outlet opening of said bafile assembly for preventing rainfrom entering said housing, a motor mounted within said upper housingportion in covering relation to a central opening through said platemember, said motor having a casing with openings in the upper and lowerends thereof, the openings in the lower end of said casing communicatingwith said opening in said plate member, the internal portions of saidmotor being arranged to permit air to pass therethrough, said motorincluding a motor shaft which extends through said casing and theopening in said plate member and supportingly engages said fan forrotation therewith, a back plate on said fan, said back plate includingan outer ring-shaped section and an inner bowl-shaped section, verticalfins extending upwardly from said ring-shaped section for cooling thelower end of said motor, the upper housing portion being proportioned soas to enclose said motor and having a lower end section which extendsslightly over and is spaced outwardly from the edges of said platemember, said upper housing portion being hingedly connected alongopposite sides thereof and adjacent its lower end to tab members whichextend outwardly from the upper end of said lower housing portion, thespace between the lower edge of said upper housing portion and theadjacent portion of said lower housing portion providing air inletsthrough which air may enter the upper portion of said housing, moveupwardly along the outside of said motor casing and be drawn throughsaid motor upon the operation of said fan to thereby cool the motor.

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